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1KWp Solar Power Plant

January 30th, 2013 Leave a comment Go to comments

Phew! What a relief!

I have just finished installing a 1KWp solar power plant in my apartment.  It was an wonderful and tiring experience getting everything to work together, ofcourse with the help of several kind people who helped moving on with the work.  I think, my installation is the first domestic installation for a capacity >1KWp in my entire area, that is Thirumullaivoyil; may be the first in Ambattur + Avadi townships.  Whatever be it, I am very happy that I could get it up and running as per the plan.  The power plant can produce upto 4-5KWh everyday in winter+sunny and may be 5-6KWh in summer.  I have been able to attach everything in my home except for Fridge, Ovens, Water heater, A/C and washing machine.  Yeah! Mixie, Coffee Maker, Wet Grinder, Computers, Water purifier run in solar at my home!  I tried attaching Fridge to the unit, but the backup time in the nights drastically reduced.  By the way, the solar power supply is 24hours through out.  The secret is that the excess power produced in the day are backed up in huge batteries, so that the saved energy is dispensed through out the night for powering my bed room and other low power night utilities.

Things to procure for this DYI project:

  1. Solar Panels: There are several variety of panels available, but always choose polycrystalline (aka multi-crystalline) panels, as there are very efficiently within 30 degree deviation of sunlight inclination angle.  If you go for monocrystalline, they are efficient only when the sun is right on top of them, so you are forced to install a solar tracking device for an additional cost.  I had procured MNRE approved panels for Rs 46/watt including transportation and taxes from Akshayasolar.  My setup has 12V 150Wp x 6 and 100Wp x 2, put together 1100Wp of bright power.
  2. Inverter: There are several varieties of inverters available in the market. Solar Inverters are the ideal choice here, but for my specification I could not get a solar inverter within my budget.  Typically solar inverters are priced around Rs 30000 for a 1KW capacity.  So, I had decided to go to regular sine-wave inverters and convert that to a solar inverter myself.  To convert an inverter to a solar inverter, I had to get a solar charge controller and fabricate a control circuitry.  I have bought a 24V, 1.4KVA Amaron Inverter for Rs 7000, with 2 years warranty.  A typical inverter has a power-factor of 0.7 to 0.8, so I could load upto 1000W comfortably without frying the inverter.
  3. Batteries: This is the most critical part of any ESU (Energy Storage Unit), where the power is stored during surplus and released when solar incoming reduces.  On the contrary, there are EEU (Energy Export Unit), which directly converts the energy derived by the solar panels into useful power for consumption or resale back to the grid.  TANGEDCO does not buy from installations less than 1MWp, so ESU is my only option.  So storing the power, the popular choice is Exide Solar Tubular batteries.  But, I chose Sharana Batteries because their manufacturing unit is in Ambattur Industrial Estate, and their service guarantee was better than what Exide offered.  While buying batteries, one should be very careful about the capacity rating of the batteries.  By capacity, the common misnomer is the AH rating.  AH rating tells the current limits of a battery, but the capacity rating is mentioned as Cxx (eg: C10, C20, etc).  Typically, a 180AH/C20 battery is same as the 150AH/C10 battery or 100AH/C5.  In C20 rating, if the drain current should be 9A, the battery would supply energy for 20 hours.  The same battery would serve for 8.33 hours only if the drain current is 18A, but you would expect it to serve for 10 hours.  Likewise, the same battery would serve only for 2.77 hours, if the drain current was 36A where you would expect a backup time of 5 hours (see here the capacity has halfed!!).  I have purchased 2x180AH @C20 tall tubular batteries from Sharana with 2 years warranty for Rs 26000.
  4. Charge Controller: There are two types of charge controllers available namely PWM, MPPT. Solar panels, although rated as 12V, they generate voltages upto 21.6V (open-circuit).  They are optimal at around 16.4-17.4V, which is called the maximum power point.  In order to leverage the maximum power from the controller, I used MPPT charge controllers.  For 1.1KW at 24V, the Imax is 50A, but assuming 80% efficiency for panels, 40A MPPT is sufficient.  I got 40A 24V controller from Adaptek India, Adyar for Rs 13600 with 3 years warranty.
  5. Structure Fabrication: This is the messy part of the entire exercise as readymade units were not available.  Since I will be using 8 panels in total and I had to use just 100 sq.ft of space on the roof, I planned to build a two row beam structure to take the load.  The weight of a panel is roughly 10kg, to 40kgs per structure is the setting.  The design shall have a rectangular frame of size 10’x3′ made out of 1.5″ L section of steel.  The rectangular section shall be supported by two 2″x1″ C channel steel of height 1.5′, which I call the legs.  The legs shall rest on a 8″x8″ 6mm plate, which in turn shall be secured to the roof with four 10mm anchor-flush bolts.  I could get raw material and fabrication done in Mannurpet, Ambattur for Rs 8000.  The total weight of steel I had installed is about 50Kg to keep the 70Kg of panel structure load secured.

Solar Power Plant Sizing chart is here.

More to continue..

  1. January 31st, 2013 at 01:43 | #1

    great. very useful information. carry on the good work.

  2. Siva
    February 25th, 2013 at 09:54 | #2

    Great insights. Keep up the good work. It will help many people to understand the possibility of such installations.

  3. athul
    February 27th, 2013 at 21:40 | #3

    great work…i want to do the same in my home….if u dnt mind kindly message me to 9961415845..i will call u back

  4. Raghavendra Sondur
    April 21st, 2013 at 14:30 | #4

    Congratulations !! This is a great achievement! You are truly an
    inspiration for all!!
    I have a couple of questions:
    a) If you decided to add another 1 KWp, which parts you can use
    and which ones would need replacement with higher capacity?
    Would it scale?
    b) I had read somewhere that the increase in temperature of the
    panels reduces their efficiency. With the summer on, do you see
    any impact?
    c) Do you plan to apply for any benefit from Govt. subsidy for
    the costs incurred?

  5. sudarsun
    April 21st, 2013 at 23:08 | #5

    Mr Raghavendra, thanks for the appreciation.

    To answer your question:

    a) If I were to extend the plant by an additional 1KW, I would have nothing to change as my controller is rated 60A, which can comfortably handle the increased current. But, with just two batteries (180AHx2) the increased solar power incoming will be overwhelming and when the load is not there, the power available would not be stored as the batteries would be overflowing quickly. So, if I have to expand, I can attached additionally two more batteries and connect them in parallel, which would make my system (180AHx2x2), to have double the storage capacity.

    b) Yes that is correct. When the temperature of the panel increases, the efficiency will drop by 10% or so. I originally wanted to create a water bath for the panels, such that the panels would convert light to electricity and the water bath would become my solar water heater. The bath would keep the panels relatively cooler and I could get hot water as well. I am yet to spend some time on the design of that system, whatever I said is just the theory waiting to go practical. 🙂

    c) No, I don’t. If I do things myself, I can do it with a price better than the subsidy fetching route. To get subsidy, I have to go the authorized dealers listed by TEDA. Their pricing is just too much to afford. For example as on today, an authorized vendor would charge atleast 2.5L per KWp. After subsidy of say 30%, the price is 1.75L. If I could do this myself, I can finish in 1L. There are some other vendors, who are willing to setup the plant for ~1.5L after 30% discount, but they use PWM based solar inverters which are very cheap compared to MPPT based units. NOTE: don’t things yourself requires engineering insights and lots of patience to get things up and running. 🙂

    Best wishes.

  6. vinay rajput
    July 24th, 2013 at 11:57 | #6

    Hi..congratss..great work!!

    Can u provide me the detailed specifications of products & any block diagram or control diagram for the the same.
    It’ll be a great help.

  7. sudarsun
    July 24th, 2013 at 17:48 | #7

    Vinay, majority of the details are mentioned in the blogpost itself. You may also refer to http://sudarsun.in/blog/2013/04/1-5kwp-solar-power-plant/ for details on another deployment. What do you mean by control diagram? The overall workflow is Panels -> MPPT Controller -> Battery -> Inverter -> A/C load. Sometimes Inverter+MPPT controller are available in one package (aka Solar Inverters). Let me know if you further information.

  8. Pawan
    October 25th, 2013 at 19:58 | #8

    Great going. You inspired me. Am also an electronics hobbyist and solar admirer.. you have done a splendid job

  9. sudarsun
    October 26th, 2013 at 11:41 | #9

    Thanks Pawan. If you need help in setting this up in your place, ping me.

  10. JAGAN N
    December 24th, 2013 at 00:29 | #10

    what is the total instalation cost??

  11. Sidambaram
    June 20th, 2014 at 13:57 | #11

    Please let me know your contact details
    Mine is mmsidambaram@gmail.com. I am in Chennai.

  12. Jyothi
    July 16th, 2014 at 09:49 | #12

    Excellent work.

    1) How reliable is the system since the install. What problems have you encounterd post-install? How did you assess the reliability of the power electronics?

    2) Which solar panel vendors have you shortlisted? What was the criteria for choosing “Akshay Solar”?

  13. sudarsun
    July 16th, 2014 at 11:27 | #13

    1. There are no problem per se, except for cleaning the panels once in 2 weeks and changing the angle of the panel thrice per year.
    2. The panels are definitely reliable, except that they perform less when the temperature shoots up. Basically, if the panel temperature can be brought down, the efficiency can be higher. The temperature shoots up during summer. When it rains, there is nothing from solar energy possible.
    3. Akshya Solar has been my regular supplier for panels. They are friendly towards small customers like me.

  14. Jyothi
    July 16th, 2014 at 17:20 | #14

    Good. How much warranty does Akshay Solar offer on their panels ? How was the panels shipped by them from their manufacturing site ?

  15. Jyothi
    July 17th, 2014 at 20:17 | #15

    I am planning to upgrade my existing inverter based power backup system to solar due to excessive power outages in my native place. I am inspired by your work and need your advice & help in setting up a small system (1 KWp). Please allow me to be very specific and ask a few questions even though they may appear irrelevant or lengthy.

    1) How did you short-list the various vendors (adaptek & emerson).for the power electronics. Are their systems rugged & reliable?

    2) Do you monitor your system parameters (various voltages, currents) on a regular basis to assess whether the power electronics are performing as intended/claimed? Why I am asking this question is because there are tons of fake vendors out there – e.g, many MPPT charge controllers are not truly MPPT and Many PWM controllers are actually ON/OFF types.

    3) You have to ensure that your batteries are correctly getting charged using a 3 stage charging protocol. It is desirable that the voltages and wishfully the “absorption stage” time should be progrmmable. Otherwise, within a very short time your costly tubular batteries will be junked (whatever the warranty might say).

    4) I believe your controllers have digital display. What parameters do they display? Have you checked if they are being correctly displayed?

    Sorry for being persistent, but one cannot be too careful in the real world.

    best regards


  16. sudarsun
    July 17th, 2014 at 20:43 | #16

    Hello Jyoti,

    I appreciate you being meticulous and specific. Here are the answers.

    shortlisted Adaptek because they are operating from Chennai and they
    gave 3 years warranty for the controller. I had spoken to several other
    vendors of controllers, but none of them were willing to offer service
    and warranty. I got another controller from China for a much lesser
    price. Infact I am using the chinese controller for the past 2+ years
    and not the one got from Adaptek. I bought Adaptek as a redundant
    controller, as I was heavily experimenting.

    shortlisted Emerson for 2KWp usage but I am using Amaron Inverter for
    my home (1.4KVA). Emerson provides service and support in Chennai and
    other players were not avaiable for a home user like me. As for Amaron
    Tribal Inverter, it is rock solid so far (operating almost 24×7 in
    inverter mode). If you go for Emerson Solar inverters, you don’t need to buy mppt controller as it is already present in the inverter.

    the controller nor the inverter has digital display. So I have setup
    an annunciating system to display the Solar Voltage, Battery Voltage,
    Load Current, Solar Incoming Current. I monitor the parameters
    regularly. The chinese controller is indeed working at a peak efficient
    of 96%. The controller also does 3 stage charging, although it ends up
    at equalization voltage (29.9V in my case). Since, I am always on
    Solar current, the controller will be in Bulk mode all the time. When
    there is no load, it adapts 3 stage charging. The charging parameters
    are settable via a rotary switch. In Adaptek, there was only one option
    for flooded tubular batteries, so no confusion there. Adaptec
    controller settles at 28.8V and never goes beyond that.

    got my batteries inspected and the engineer said the batteries are very
    healty and the specific gravity of the electrolyte is well within the
    acceptable range. So settling at 29.9v (equalization) or 28.8 (absorb)
    are both doing well.

    The panels
    were transported via courier service with nice packaging and the panels
    reached my place in pristine condition. The vendor gave 15 years
    warranty for the panels.

    Out of
    curiously, which is your native town? Whatever you do, please ensure
    service & support availability for different parts of this project.

    Sudarsun S.

  17. Jyothi
    July 17th, 2014 at 21:30 | #17

    Thanks for such fast and detailed response. I am very impressed.

    1)By any chance, is the chinese controller from EPSolar (Tracer Make) ? I believe these guys make good controllers at a reasonable rate. An 40A MPPT system from them with digital display and programmable voltages is available at 18000/- (Please check ebay.in for the latest pricing)

    2)I am very much doubtful if Emerson guys will provide service & support in my native place. By the way, my native place is remote village in Chhattisgarh – called Ratanpur. Ensuring support & servicing for my system in the remotest corners of the world is the biggest challenge. Ironically, these remote corners are the ones that need these systems the most. Can you provide any insights about how this can be ensured?

    3)Can you guide me briefly how to setup an annuciating system myself (I am not a brilliant Electronics Engineer like you). Secondly,I have not really understood why the controller has to put the battery in “bulk” always in an off-grid system like yours. Does this mean that you have under-sized your battery bank and therefore you are deeply discharging it by more than 30-40% SOC. If this is so, will your battery life not suffer ?

    4) 15 years is good for panels. More is probably useless. Who knows whether these guys will survive for 15 years?

    Anyways, thanks for the detailed responses. I really appreciate.



  18. Jyothi
    July 18th, 2014 at 10:08 | #18

    Thanks for the prompt reply. Really appreciate.

    1) Can you briefly guide as to how to build an annunciating system like the one you have installed ? Without monitoring the parameters like you do you are driving in a blind alley waiting for an accident.

    2) I believe your chinese controller is from EPsolar – Tracer make. these guys make good controllers at decent price (Rs 18,000/- or so for a 40 MPPT controller with digital display and programming voltage – please check ebay.in for latest prices).

    3) Your idea of solar inverter is much appreciated. I am serious about it. Will check warranty and service in my locality as advised. One question about Emerson solar inverter is whether you force it remain n grid only mode once in a while so that the battery acquires full charge? I can ask this question from them – but I am doing it here for the benefit of our readers.

    4) Regarding battery charging, I have not really understood one point. Why should controller put your battery on “bulk mode” when you are drawing solar current. Does this mean that you have underdesigned your battery bank? Isn’t it better that you don’t deeply discharge them by more than 30% of SOC for a truely long battery life? If this so, then the controller should mostly clock between “absorption” and “float”. Why this is important is that batteries are really pricey and if you have to replace them once every 3-5 years, your system will never pay for itself and only be an expensive toy of the few privileged.

    5)By the way, my native place is in Chhatiisgarh (near capital city of Raipur).

    best regards


  19. sudarsun
    July 18th, 2014 at 14:26 | #19

    My annunciation system display the V, I values of the running system. Given that the MPPT controller has an inbuilt battery charger controller, it is taking care of protecting the battery from deep discharge and overcharge. Do you recommend monitoring any other parameters per se?

    My chinese controller is not Tracer, but Adaptek controller is originally Tracer. I don’t recall the chinese vendor name, but can find it from my mailbox.

    Emerson solar is off-grid type and it works on solar power (charges battery from solar) when it’s available and changes over to battery (no charging now) when solar is not available. Upon reaching a configurable lower cutoff, it changes to grid (and charges battery from grid). The solar inverter can be configured to be aggressively solar where maximum solar power could be used for delivery.

    The connection is solar->mppt->battery->inverter. So, the traditional battery charging strategies are not applicable, as the battery voltage would be changing depending on the load on the inverter. i don’t deep discharge the battery. in fact conservatively, the battery is allowed to discharge only upto 23V max, but in general i change over to grid, when the battery voltage drops just below 24V. That’s why, my battery’s health is going well even after 2 years with 24×7 usage (maximum of 2 charge-discharge cycles per day).

  20. sudarsun
    July 18th, 2014 at 14:31 | #20

    When I bought the controller, I spent just 9000/- for the chinese controller and about 12500/- for the Adaptek controller (40A 24V rating).

    Emerson is out of the equation for remote places. So, the best deal is to have a vendor from the neighboring city (ex: Bangalore). There are few vendors who are willing to travel to remote places for offering service, but at an additional cost. http://www.unipar.in is one vendor who was willing to travel. In general, if you size your solar inverter solution to 2x-3x of the required capacity, preventive maintenance would be sufficient, as the solar solution is operating well under “very safe” conditions.

    My battery bank is under sized of course, so during the day, when there is not much load i will be wasting the unused power 🙁 But as said before, I never deep discharge the battery.

  21. Jyothi
    July 18th, 2014 at 16:35 | #21

    I believe you should regularly monitor all voltages are currents. Battery State of Charge (by electrolyte specific gravity) should also be monitored periodically. Absorption and equalisation times maybe important – but there maybe no way to control these.

    I have not understood when you say traditional battery charging protocol is not followed in your case. If you see the technical brochure of any MPPT controller like Tracer, they advertise “3 stage” or “4 stage” PWM charging. Which probably means that they are designed to charge the battery in a traditional way.

    Battery being connected to the load may make little difference to the charging protocols. Please correct me if I am wrongin my understanding- what is probably happening is that during the day when there is load as well as battery charging, controller supplies the energy directly to the load. This is also more energy efficient. During night the batteries service the loads only. Thus, during day batteries are getting charged only and during night they are getting discharged only. Under such a scenario, traditional charging and discharging should hold good.

  22. Jyothi
    July 22nd, 2014 at 15:25 | #22

    I believe roof-top solar is set to make it in a big way. because of 2 reasons:
    i) Tata power solar (TPS) have recently launched a roof-top installation service called Dynamo which seems to be offered at a very reasonable rate. They provide Tata BP panels + PCU + locally procured solar batteries. They give 25 year warranty for panels + 5 years warranty for BOS. Their PCU is likely to be good because they were partners with Emerson for some time when they used to make Tata Liebert products in India. There dealer network has widened to what I believe to be ~1000 dealers from across the country.

    2) TPS dealers do the paper work for you for state & central subsidy and some of them offer part of the subsidy amount upfront. This makes the deal even more juicier.

    I believe they are gunning for the kill because their deals may compare well with the costs projected by you for your home installations Do check out their website here:


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